Percussion Hammer Bit with Overlapping Cutter Rows
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Solution Overview
Problem
Conventional percussion drilling bits face challenges in maintaining efficient drilling speed and bit durability, leading to increased drilling time and costs due to premature wear of gage cutting elements, which are susceptible to excessive linear velocities and distance travel during drilling operations.
Innovation Solution
The design incorporates a hammer bit with radially overlapping cutting elements in circumferential rows, where the cutting profiles of adjacent and inner row cutter elements overlap, distributing loads and reducing stress on gage cutter elements, enhancing durability and service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hammer bits use separate circumferential rows of cutting elements, then the bit structure is simpler and easier to manufacture, but the gage cutter elements experience excessive linear velocities and distance travel leading to premature wear
Solution Approach 1:
The patent merges adjacent circumferential rows of cutting elements by providing radial overlap between the cutting profiles of different rows. Specifically, the inner row cutting elements radially overlap with the outer row cutting elements, creating a combined cutting structure that reduces the travel distance and linear velocity of individual gage cutter elements while maintaining borehole gage control.
2Productivity
If the bit rotates at higher speeds to increase drilling productivity, then drilling speed improves, but the gage cutter elements experience increased linear velocities leading to accelerated wear
Solution Approach 1:
The patent transitions from a single-row circumferential arrangement to a multi-row arrangement with radial overlap. This dimensional change in the cutting element configuration allows the system to accommodate higher rotational speeds by distributing the cutting action across multiple overlapping rows, thereby reducing the linear velocity and wear on individual gage cutter elements while maintaining or increasing overall drilling productivity.
3Reliability
If the hammer bit impacts the same portion of earth without indexing, then the impacting mechanism is simpler, but the cutting elements experience concentrated wear and reduced durability
Solution Approach 1:
The radial overlap of cutting elements from adjacent rows creates a combined cutting zone that naturally distributes the impact across multiple elements. This merged configuration enhances the effectiveness of indexing by ensuring that as the bit rotates, multiple overlapping cutting profiles engage fresh formation material, thereby reducing concentrated wear on individual elements and improving overall cutting element durability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the durability and service life of the bit by distributing axial loads across overlapping inserts, reducing stress on gage cutter elements and maintaining borehole diameter, thereby improving drilling efficiency and reducing the frequency of bit replacements.
Implementation Method 1
the earth disintegrating action of the hammer bit is enhanced by providing a plurality of cutting elements that extend from the cutting face of the bit for engaging and breaking up the formation
Implementation Method 2
the borehole is formed as the impact and indexing of the drill bit, and thus cutting elements, break off chips of formation material which are continuously cleared from the bit path by pressurized air pumped downwardly through ports in the face of the bit
Data Source
AI summary
A hammer bit includes a bit body having a bit axis and a bit face, a first circumferential row of cutting elements mounted to the bit face, the first circumferential row located at an outermost radius of the bit face and extending around the bit axis, and a second circumferential row of cutting elements mounted to the bit face, the second circumferential row located radially inwardly adjacent the first circumferential row, wherein each of the cutting elements of the second circumferential row is a semi-round top insert. The ratio of the radial overlap distance to the radial span distance between the cutting profiles of cutting elements of the first and second circumferential rows is between 0.1 and 0.5. The ratio of the radial overlap distance to the radial span distance between the cutting profiles of the first and second circumferential rows is greater than 0.25.